1. Field of the Invention
The present invention relates to a module TV, and more particularly to an improved module TV and control method thereof which effectively corresponds to a customized module TV by selecting a module type requested by a customer at an initial step of its production.
2. Description of the Background Art
As shown in FIG. 1, a general module TV includes: a key input unit 1, a tuner card 2 for receiving a broadcast signal; a PIP (Video-In-Video) card 3 for PIP-processing the broadcast signal received from the tuner card 2; a microcomputer 4 for carrying out a general control operation of the module TV; a switching unit 5 for switching an external video signal and the broadcast signal outputted from the tuner card 2; a video/audio processing unit 6 for processing an external video sign or a broadcast signal received from the switching unit 5; and card connection units 7.about.10 for electrically connecting the tuner card 2 and the PIP card 3 to an internal circuit provided in the module TV.
The tuner card 2 includes: a tuner 2-1 for selecting a broadcast signal of a desired channel; an IF (Intermediate Frequency) processing unit 2-2 for converting the broadcast signal of the selected channel to an IF signal and then branching the converted IF signal to a video signal VS1 and an audio signal AS1; and an audio processing unit 2-3 for processing an audio signal AS1 outputted from the IF processing unit 2-2. Here, the PIP card 3 is provided with a color demodulator 3-1 and a PIP processing unit 3-2.
The switching unit 5 includes: a first switch 5-1 for switching an externally applied video signal VS2 and a video signal VS1 outputted from the IF processing unit 2-2 under the control of the microcomputer 4; and a second switch 5-2 for switching an externally applied audio signal AS2 and an audio signal AS2 outputted from the audio processing unit 2-3.
The video/audio processing unit 6 includes: an audio control unit 6-1 and an amplifier 6-2 for processing and outputting to a speaker 6-3 the audio signal AS1 or AS2 outputted from the second switch 5-2; and a chroma unit 6-4 and a deflection unit 6-5 for processing the video signal VS1 or VS2 outputted from the first switch 5-1 and displaying the precessed signal on the color receiving tube 6-6. The operation of the thusly constituted conventional module TV will now be described with reference to the accompanying drawings.
First, the microcomputer 4 carries out a step for recognizing cards if they are mounted in the module TV.
That is, the microcomputer 4 resets a builtin error counter (not shown), outputs through output terminals OUT1, OUT2 and an option terminal P low level signals which are equivalent to those in FIGS. 2A through 2C, and reads, at point A, signals applied from the key input unit 1 to the input terminals IN1.about.IN4.
Then, the microcomputer 4 compares levels of the signals between at the input terminals IN1.about.IN4 and at the option terminal P. At this time, when the two signal levels are different from each other, the signals at the input terminal is recognized as one at the option terminal P and then the above step is once again carried out; when the two signal levels are equal, a counter value in the builtin error counter (not shown) is increased by "1".
Thereafter, the microcomputer carries out such a card acknowledgement step several times, and when the counter value in the error counter (not shown) becomes "10", it is determined whether there are cards and which kinds of cards they are, in accordance with signal levels of the input terminals IN1.about.IN4.
In other words, when the microcomputer 4 outputs a low level signal to the option terminal P in order to determine whether cards are mounted, assuming that the tuner card 2 is mounted in the card connection unit 7, a diode D1 of the tuner card 2 is turned on by the low level signal of the option terminal P.
Subsequently, current i flows from the input terminal IN1 towards the output terminals OUT1, OUT2, whereby the signal at the input terminal IN1 is recognized as a low level, whereas the signals at the input terminals IN.about.IN4 without cards mounted therein are recognized as high levels. At this time, the above acknowledgement is similarly applied to a case in which the PIP card is mounted in the card connection unit 10 or a card is mounted in the card connection units 8-9.
Therefore, the moment when the counter value in the error counter (not shown) becomes "10", the microcomputer 4 determines that when the signals at the input terminals IN.about.IN4 are at low levels there are mounted cards and when the signals at the input terminals IN.about.IN4 are at high levels there are not mounted cards.
When the card acknowledgement step is completed, the microcomputer 4 carries out a control operation according to the kinds of the recognized cards.
Firstly, when neither of the tuner card 2 and the PIP card 3 is mounted, the microcomputer 4 controls the first and second switches 5-1, 5-2 of the switching unit 5, whereby externally applied video signal VS2 and audio signal AS2 may be inputted to the video/audio processing unit 6.
Secondly, when only the tuner card 2 is mounted, the microcomputer 4 controls the first and second switches 5-1, 5-2 in the switching unit 5 are controlled, whereby the video signal VS1 and the audio signal AS1 outputted from the tuner card 2 may be inputted to the video/audio processing unit 6.
Thirdly, when both the tuner card 2 and the PIP card 3 are mounted, the microcomputer 4 controls the first and second switches 5-1, 5-2 in the switching unit 5, whereby the video signal VS1 and the audio signal AS1 outputted from the tuner card 2 and the video signal VS3 PIP-processed in the PIP card 3 may be inputted to the video/audio processing unit 6.
Fourthly, when the PIP card 3 is mounted, the microcomputer 4 controls the first and second switches 5-1, 5-2 in the switching unit 5, whereby the externally applied video signal VS2, audio signal AS2 and the video signal VS3 PIP-processed in the PIP card 3 may be inputted to the video/audio processing unit 6.
Thereafter, the audio signal (AS1 or AS2) inputted to the video/audio processing unit 6 becomes regenerated at the speaker 6-3 through the audio control unit 6-1 and the amplifier 6-2, and the video signals VS2, VS3 are inputted to the color receiving tube 6-6 through the chroma unit 6-4. The color receiving tube 6-6 displays the video signals together with the PIP screen under the control of the deflection unit 6-5.
However, the conventional module TV employs diodes at respective function cards so that two connection lines per function card are required to electrically connect an TV interior with the respective card in addition to the control line.
As a result, in order to increase function cards in number, the equivalent number of connection lines should disadvantageously be increased, whereby not only should mountable function card number be limited but respective locations for recognizing relevant function cards should also be fixed, thereby increasing a design burden.